Antihypertensive efficacy of night-time graded-release diltiazem versus morning amlodipine in African Americans.

Background: The effect of a once daily night-time (10 pm) graded-release diltiazem (GRD) on early morning blood pressure (BP), heart rate (HR), and rate-pressure product (RPP) were compared with the effect of morning (8 am) amlodipine in 262 African American individuals with hypertension.

Methods: The multicenter, randomized, double-blind, parallel-group, dose-to-effect trial evaluated changes from baseline in BP, HR, and RPP (HR x systolic BP) by ambulatory BP monitoring during the first 4 h after awakening (diastolic BP = primary), between 6 am and 12 noon, and over a 24-h period. Patients were randomized to night-time GRD 360 mg (n = 132) or morning amlodipine 5 mg (n = 130) for 6 weeks, and were titrated to GRD 540 mg or amlodipine 10 mg after 6 weeks if clinic systolic BP/diastolic BP (SBP/DBP) was > or = 130/85 mm Hg.

Results: Compared with amlodipine, GRD showed significantly greater DBP reductions of 3.5 mm Hg (P < .0049) and 3.2 mm Hg (P < .0019) during the first 4 h after awakening and between 6 am and 12 noon respectively, as well as comparable reduction for the 24-h mean DBP. The SBP reductions during the morning periods were comparable, but the reduction in the 24-h mean SBP was 3.4 mm Hg greater (P < .0022) for amlodipine. Mean reductions in HR and RPP were significantly greater (P < or = .0008) for GRD during all intervals; amlodipine increased whereas diltiazem reduced HR with mean differences of 6.7 to 9.3 beats/min. Both treatments were well tolerated.

Conclusions: Night-time GRD was more effective than morning amlodipine in reducing early morning DBP, HR, and RPP, as well as 24-h HR and RPP in African American individuals with hypertension. Amlodipine was more effective in reducing SBP over the 24-h period.